The present invention relates to methods for detecting and diagnosing electrical faults in electrical control systems.
The early detection and diagnosis of electrical faults in electronic components and control systems is extremely beneficial to the overall system operation. A short circuit (i.e. a short to ground or a short to supply) on one of the system""s control lines could damage a driver or other components connected to that control line causing a more pronounced system failure.
Prior art integrated circuits typically incorporate event or fault detection strategies. Half bridge drivers offered by Infineon Corporation such as, the TLE 4207 dual half bridge driver, typically are used to control the operation of DC motors and are an example of a circuit having fault detection capability. This motor driver has built-in features such as diagnosis, over and under voltage lock-out, short circuit protection and over temperature protection to reduce the damage caused by a failure. An error flag is provided as an output of this driver device for detecting and diagnosing electrical faults on the two outputs of the device. For example, if the error flag is set high, then no error has been detected. If the error flag is set low, then there is an over temperature fault or an over voltage fault present.
While prior art fault detection schemes achieve their intended purpose, particular applications required improve diagnostic and fault detection methods. For example, the fault detection scheme implemented in Infineon""s TLE 4207 device is only able to communicate whether a fault exists on the output control lines and not which one of the two output control lines the fault is present. In other words, this fault detection scheme does not indicate which output line has a fault associated with it.
In certain applications it is desirable to have each output line of a driver, such as the TLE 4207 dual half bridge driver, control a component or device, in contrast with the conventional approach, where two control lines are used to control one component. Unfortunately, present error or fault detection schemes do not provide an indication as to which control line is experiencing a fault.
Therefore, it would be desirable to have a new and improved method for detecting faults in electrical control lines. This method should provide the type and location of the fault. More specifically, the new and improved method should determine on which control line the fault exists.
In an aspect of the present invention a method for detecting faults in an electrical system having a plurality of control lines and an error flag or indicator line is provided. This method determines which of the plurality of control lines are active and whether the error flag line is indicating a fault is present.
In another aspect of the presenting invention, one of the plurality of control lines is deactivated when the error flag line is indicating that a fault is present.
In another aspect of the present invention, the method re-determines whether the error flag line is indicating a fault is present and then determines that a fault is present on the deactivated control line when the error flag line indicates that a fault is no longer present.
In a further aspect of the present invention, the method re-activates the deactivated control line when the error flag line indicates that the fault is still present. These steps are repeated until the control line having a fault is identified.